worksheet of chapter 3 class 9
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IMPORTANT QUESTIONS
1 MARK QUESTIONS
Question. 1. Name the scientist who laid the foundation of chemical sciences. How ?
Answer. Antoine Laurent Lavoisier, by establishing two important laws of chemical combination.
Question. 2. Define law of conservation of mass.
Answer. It states that, ‘Mass is neither created nor destroyed in a chemical reaction.’ In other-words, the mass of the reactants must be equal to the mass of products.
Question. 3. Define law of constant proportion.
Answer. It states that, ‘In a pure chemical substance, the elements are always present in definite proportions by mass’.
Question. 4. Which organisation approves the names of elements all over the world ? Write the symbol of gold. [SA II-2014]
Answer.
1 MARK QUESTIONS
Question. 1. Name the scientist who laid the foundation of chemical sciences. How ?
Answer. Antoine Laurent Lavoisier, by establishing two important laws of chemical combination.
Question. 2. Define law of conservation of mass.
Answer. It states that, ‘Mass is neither created nor destroyed in a chemical reaction.’ In other-words, the mass of the reactants must be equal to the mass of products.
Question. 3. Define law of constant proportion.
Answer. It states that, ‘In a pure chemical substance, the elements are always present in definite proportions by mass’.
Question. 4. Which organisation approves the names of elements all over the world ? Write the symbol of gold. [SA II-2014]
Answer.
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